Ilitek ILI210x/ILI2117/ILI251x touchscreen controller

Required properties:
- compatible:
    ilitek,ili210x for ILI210x
    ilitek,ili2117 for ILI2117
    ilitek,ili251x for ILI251x

- reg: The I2C address of the device

- interrupts: The sink for the touchscreen's IRQ output
    See ../interrupt-controller/interrupts.txt

Optional properties for main touchpad device:

- reset-gpios: GPIO specifier for the touchscreen's reset pin (active low)

Example:

	touchscreen@41 {
		compatible = "ilitek,ili251x";
		reg = <0x41>;
		interrupt-parent = <&gpio4>;
		interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
		reset-gpios = <&gpio5 21 GPIO_ACTIVE_LOW>;
	};